Method and apparatus for reducing sample dispersion in turns and junctions of microchannel systems

Abstract

What is disclosed pertains to improvement in the performance of microchannel devices by providing turns, wyes, tees, and other junctions that produce little dispersion of a sample as it traverses the turn or junction. The reduced dispersion results from contraction and expansion regions that reduce the cross-sectional area over some portion of the turn or junction. By carefully designing the geometries of these regions, sample dispersion in turns and junctions is reduced to levels comparable to the effects of ordinary diffusion. The low dispersion features are particularly suited for microfluidic devices and systems using either electromotive force, pressure, or combinations thereof as the principle of fluid transport. Such microfluidic devices and systems are useful for separation of components, sample transport, reaction, mixing, dilution or synthesis, or combinations thereof.

What is claimed is:  
     
       1. A low-dispersion microchannel device for dividing a sample comprising: a branching junction having one inlet end and at least two outlet ends, an inner wall and an outer wall, at least one contraction region, at least one constricted region, and at least one expansion region, wherein a portion of the constriction region has a cross-sectional area that is smaller than that of at least one outlet end, and wherein the branching junction has a cross-section that is rectangular, trapezoidal, or triangular. 
     
     
       2. The low-dispersion microchannel device of  claim 1 , wherein the branching junction has a cross-section that is rectangular. 
     
     
       3. The low-dispersion microchannel device of  claim 1 , wherein the branching junction has a cross-section that is trapezoidal. 
     
     
       4. The low-dispersion microchannel device of  claim 1 , where the branching junction has a cross-section that is triangular. 
     
     
       5. A low-dispersion microchannel device for joining two or more sub-samples comprising: a confluence junction having two or more inlet ends and one outlet end, an inner wall and an outer wall, at least one contraction region, at least one constricted region, and at least one expansion region, wherein a portion of the constriction region has to a cross-sectional area that is smaller than that of at least one inlet end, and wherein the confluence junction has a cross-section that is rectangular, trapezoidal, or triangular. 
     
     
       6. The low-dispersion microchannel device of  claim 5 , wherein the confluence junction has a cross-section that is rectangular. 
     
     
       7. The low-dispersion microchannel device of  claim 5 , wherein the confluence junction has a cross-section that is trapezoidal. 
     
     
       8. The low-dispersion microchannel device of  claim 5 , wherein the confluence junction has a cross-section that is rectangular. 
     
     
       9. A low-dispersion device for turning the direction of transport of a moving sample that comprises: a microchannel system comprising at least one turning channel having an inlet end and an outlet end, an inner wall and an outer wall, and an included turn angle, wherein the turning channel comprises contraction and expansion regions such that a portion of the turning channel is constricted to a width that is smaller than the widths of the inlet and the outlet ends, wherein the contraction and expansion regions define inner and outer walls of the turning channel that differ in length by less than the product of the included turn angle and the larger of the widths of the turning channel at the inlet end and outlet end. 
     
     
       10. A low-dispersion device for dividing a sample that comprises: a planar substrate patterned to define a microchannel system comprising at least one branching junction having one inlet end and at least two outlet ends, an inner wall and an outer wall, at least one contraction region, at least one constricted region, and at least one expansion region, wherein the constriction region has a width that is smaller than the width of at least one outlet end. 
     
     
       11. The low-dispersion device of  claim 10  having one inlet end and two outlet ends wherein the sum of the widths of the two outlet ends is substantially equal to the width of the inlet end.